1. Field of the Invention
The invention relates generally to the field of printer ink cartridges and, more particularly, to a high throughput inkjet printer cartridge having two or more inkjet nozzle arrays.
2. Description of the Related Technology
Inkjet cartridges are used in inkjet printers which are a class of non-contact printers characterized by rapid heating and expulsion of ink from nozzles on one or more inkjet cartridges onto a recording medium, e.g., paper. Many inkjet cartridges are passive devices, i.e., use passive components on a jet plate assembly, such as resistors, to heat the ink in the cartridge to a point at which the ink is expelled from jet nozzles or openings in the jet plate. The resistors are formed utilizing thick or thin film technology on a substrate. Typically, one resistor per orifice or jet is required.
In multi-color ink jet printing, an image is assembled from several overlaid color planes. Each color plane comprises an array of ink droplets of a particular color deposited on a two dimensional grid. The grid size is defined by the resolution of the printer, and is typically 150, 300, or 600 dots per inch in each dimension. To produce an image, multiple ink jet print heads (typically four), one for each color, are passed over the media, and each printhead selectively ejects droplets of ink onto the appropriate grid locations to produce the color plane associated with that print head. Generally, the print heads comprise a jet plate having a vertically extending array of nozzles spaced apart according to the print resolution, i.e. {fraction (1/150)}th , {fraction (1/300)}th, or {fraction (1/600)}th inches apart, in the vertical direction. The printed image is produced by passing the printhead over a horizontal band of the media, depositing the appropriate drops of ink, incrementing the media vertically, passing the printhead over another horizontal band of media, and so on, until the printhead has printed the entire extent of the desired image. A given color plane is thus built up from a large number of adjacent horizontal swaths of deposited ink droplets.
In performing this operation, the printer sends control signals to the resistors on the cartridge to control the firing sequence of the jet nozzles as the cartridge move along the page. One of the first printer ink cartridges that used this design was marketed by Hewlett-Packard in approximately 1984 and was sold under the trade name Think Jet Cartridge. The Think Jet Cartridge had 12 jet nozzles and required 13 interconnect lines to the printer system to control the application of ink by the cartridge. The design and operation of the Think Jet Cartridge is described in more detail in an article entitled xe2x80x9cHistory of Think Jet Printhead Development,xe2x80x9d published in the Hewlett-Packard Journal dated May, 1985.
In approximately 1987, Hewlett-Packard developed the deskjet thermal inkjet cartridge which increased the number of jets on a printer ink cartridge to fifty. Therefore, the deskjet cartridge requires fifty-six interconnect lines to the printer system to control the application of ink by the cartridge. The design and operation of the original deskjet cartridge is described in more detail in an article entitled, xe2x80x9cLow Cost Plain Paper Printing,xe2x80x9d published in The Hewlett-Packard Journal dated August 1992.
More recently, Hewlett-Packard designed a thermal printer ink cartridge, part no. HP51640, used in a Deskjet 1200 printer also by Hewlett-Packard which incorporated a portion of the driver electronics and some control logic onto the jet plate of the printer ink cartridge. In this particular case, the jet plate is composed of the following structures: (1) a silicon substrate which houses the driver control for each chip, (2) some control logic circuitry to determine which jet is to be fired; and (3) the heat generating resistors. Since the driver control circuitry and the control logic circuitry are proximate to the heat generating resistors, the driver control logic circuitry is susceptible to the heat generated by the heat generating resistors. The jet plate is located proximate to the jet nozzles to heat the ink for expulsion. The design and operation of the Deskjet 1200 cartridge is described in more detail in two articles entitled, xe2x80x9cThe Third-Generation HP Thermal Inkjet Printheadxe2x80x9d and xe2x80x9cDevelopment of the HP Deskjet 1200C Print Cartridge Platformxe2x80x9d published in The Hewlett-Packard Journal dated February, 1994.
In the case of developing a silicon integrated circuit on a jet plate to drive and control the operation of the jets, a number of factors directly affect the size of the circuitry required. Initially, each jet nozzle requires one heating element, such as the resistor, one drive control circuit and one or more control signals to indicate when the jet nozzle is to be fired. As the number of jets increases, the size of the silicon substrate required to house the driver circuits, control circuits, and the heating elements increases proportionally. Also, the increased number of jets, for example 84 jets, requires a silicon die having an inefficient shape or having a large aspect ratio, i.e., a die having a long length and a short width, because the increased number of jets causes the die to increase in length. Both large dies and dies with a large aspect ratio are very difficult to manufacture, further decreasing processing yields and increasing production costs.
In addition to the problems of silicon yield for such large circuits, the circuitry on the jet plate must be able to withstand the heat generated by the resistors as well as problems associated with silicon coming into constant contact with moving heated ink. Therefore, the production of the silicon integrated circuit on the jet plate must include additional steps to prevent long-term degradation of the silicon due to contact with the chemicals in the ink, and due to cavitation problems caused by the moving ink, etc. These processes increase the production cost for making a jet plate. The same processes may also decrease the performance characteristics of the driver and logic circuits on the jet plate.
Subject to the above-described manufacturing limitations, manufacturers of inkjet printer cartridges, have constantly strived to increase the number of jet nozzles per cartridge. As silicon wafer processing techniques became more advanced, it became possible to manufacture larger jet plates having a greater number of jet nozzles on a single silicon wafer with increased production yields. In later printer cartridges, the nozzle arrays included up to 104 and 208 nozzles on a single printer cartridge. With 104 nozzles on a cartridge, and a print density of 300 dpi, each pass of the printer cartridge could cover a ⅓ inch swath on the recording medium. With a printer cartridge having 208 jet nozzles, the printing speed of an image having an image quality of 300 dpi could be double that of a cartridge having only 104 jet nozzles. As one may easily calculate, a cartridge having 208 nozzles is capable of printing a 300 dpi image by printing on ⅔ inch swaths per pass of the cartridge over the recording medium. Conversely, if the printing speed is to remain the same, but the image quality is to be improved, a cartridge having 208 nozzles may print an image having a dot density of 600 dpi and print swaths of ⅓ of an inch per pass of the cartridge. Thus, as the number of nozzles on a single cartridge increases, one may increase either the printing speed, the printing quality, or both.
Recently, ink jet cartridges having 300 or more jet nozzles and a corresponding jet plate assembly have been produced. Thus, a printer cartridge having 300 jet nozzles can print an image quality of 600 dpi in increments of xc2xd inch swaths per pass of the printer cartridge over the recording medium. For a 300 dpi jet plate, the width of each swath may be 1 inch. However, these advanced printers are relatively expensive due to their high cost of manufacturing. Thus, although, the size of the silicon substrate required to house the driver circuits, control circuits and the heating elements, otherwise referred to as the jet plate herein, increases proportionally to the number of added jet nozzles, the manufacturing costs increase at a much faster rate. The increased number of jets requires a jet plate made from a silicon die having an inefficient shape, or large aspect ratio and large dies and dies with large aspect ratios are very difficult to manufacture, decreasing processing yields and rapidly increasing production costs.
This invention provides an improved printer cartridge having a greater number of jet nozzles and an improved method of manufacturing such a printer cartridge which does not have the inherent disadvantages of low processing yields and high manufacturing costs associated with prior art printer cartridges having a relatively large number of jet nozzles. The preferred embodiment of this improved inkjet cartridge includes two individual jet nozzle arrays on a single cartridge housing.
The improved inkjet cartridge of the invention provides increased print speed and further provides a significant redundant nozzle capability to increase print image reliability and quality. This improved inkjet cartridge uses two separate, easily manufactured, low cost and highly reliable nozzle arrays mounted on a single cartridge housing to provide essentially a 100% increase in print throughput without the disadvantages of the prior art.
In one embodiment of the invention, an inkjet printer cartridge includes: a rigid body having at least one chamber for containing ink therein and a substantially planar bottom surface; a first flex circuit affixed to the rigid body, which includes: a first jet nozzle array having a first plurality of jet nozzles for expelling ink onto a recording medium, the first plurality of jet nozzles being disposed along a first region of the bottom surface of the body; at least one first contact element, coupled to the first jet nozzle array, for providing electrical connectivity between the first jet nozzle array and a printer system which transmits signals to the at least one first contact element to control the operation of the first jet nozzle array; and a second flex circuit, affixed to the rigid body, which includes: a second jet nozzle array having a second plurality of jet nozzles for expelling ink onto the recording medium, the second plurality of jet nozzles being disposed along a second region, opposite the first region, of the bottom surface of the body; and at least one second contact element, coupled to the second jet nozzle array, for providing electrical connectivity between the second jet nozzle array and the printer system which transmits signals to the at least one second contact element to control the operation of the second jet nozzle array.
In another embodiment, an inkjet printer cartridge is manufactured by a process that includes: affixing a first flex circuit to a housing of the printer cartridge such that a first portion of the first flex circuit having at least one first contact element thereon is located on a first side surface of the housing and a second portion of the first flex circuit having a first jet nozzle array thereon is located on a first region of a bottom surface of the housing, wherein the at least one first contact element is electrically coupled to the first jet nozzle array and the first jet nozzle array is aligned with respect to the dimensions of the bottom surface; and affixing a second flex circuit to the housing of the printer cartridge such that a first portion of the second flex circuit having at least one second contact element thereon is located on a second side surface, opposite the first side surface, of the housing and a second portion of the second flex circuit having a second jet nozzle array thereon is located on a second region, opposite the first region, of the bottom surface of the housing, wherein the at least one second contact element is electrically coupled to the second jet nozzle array and the second jet nozzle array is aligned with respect to the first jet nozzle array such that the first and second jet nozzle arrays function as a unitary nozzle array.
In a further embodiment, a method of manufacturing an inkjet printer cartridge, includes: affixing a first flex circuit to a housing of the printer cartridge such that a first portion of the first flex circuit having at least one first contact element thereon is located on a first side surface of the housing and a second portion of the first flex circuit having a first jet nozzle array thereon is located on a first region of a bottom surface of the housing, wherein at least one first contact element is electrically coupled to the first jet nozzle array and the first jet nozzle array is aligned with respect to the dimensions of the bottom surface; and affixing a second flex circuit to the housing of the printer cartridge such that a first portion of the second flex circuit having at least one second contact element thereon is located on a second side surface, opposite the first side surface, of the housing and a second portion of the second flex circuit having a second jet nozzle array thereon is located on a second region, opposite the first region, of the bottom surface of the housing, wherein at least one second contact element is electrically coupled to the second jet nozzle array and the second jet nozzle array is aligned with respect to the first jet nozzle array such that the first and second jet nozzle arrays function as a unitary nozzle array.